This is a revised application for an institutional training grant in the Epidemiology and Biostatistics of Aging. Johns Hopkins has a critical mass of recognized faculty working in the quantitative sciences on aging research problems. Given training support, we propose to attract a small group of outstanding predoctoral and postdoctoral candidates to lead the next generation of quantitative research scientists addressing health problems of our aging population. These students will be trained as researchers who can conduct leading-edge descriptive and analytic research and develop, implement, and evaluate prevention programs that compress the morbidity experience of the aging US population. The program will be based in the Departments of Epidemiology and Biostatistics at the Johns Hopkins University, but will involve faculty from other Departments in the School of Public Health, and several departments in the School of Medicine. All candidates will be enrolled for academic degrees, either for the Master of Health Sciences or the Ph.D. in the School of Public Health. All trainees will complete a structured program of didactic course work, participate in regular journal clubs and seminar series, work with core faculty on existing and future aging research projects, and complete original thesis research worthy of peer-reviewed publication. The program director, an accomplished epidemiologist/gerontologist/geriatrician, will lead a team of twelve nationally-renowned epidemiologists (7) and biostatisticians (5) who already collaborate on a number of aging-related research and educational programs. The training program will emphasize methodology critical to effective descriptive and analytic research on complex issues of heath and aging and the design, implementation, and evaluation of population-based and clinical interventions to delay the onset of morbidity and disability. Within the overall goal of prevention in older populations, areas of emphasis will include risk factors and measurement of function, frailty, and disability; role of risk factors and chronic diseases in major adverse health outcomes associated with aging, genetic risk factors for age- related morbidity; design and conduct of large-scale prospective studies (both observational and clinical trials), longitudinal data analysis, and health services for an aging population. Graduates will be effective leaders of multidisciplinary research teams tackling the health problems associated with the aging US population.